The river Dretulja, a short, but interesting current, is apart from the river Jesenica a good example for this kind of karst-rivers in Lika. Its sources are certainly filled by the water from the Lička Jesenica, but also from the lake Begovac, which has much water in spring and which forms a huge water reservoir, but in summer it drains completely. The cave source is a truly big estavelle, which throughout the year becomes a sinkhole. In the Dretulja you can fish brown trout and big rainbow trout, which very often have several pounds and take refuge in the inaccessible and with dense twigs covered bank. Opposite to the large sinkholes of the river Jesenica, the Dretulja drains little by little in small sinkholes near the village of Janja Gora. Stajnička Jaruga is also an interesting, but somewhat larger brook. Its water originates from a sinkhole, but from the western part, at the southern side of the mountain Kapela. Here lives also the rare endemic species, the Croatian dace (Leuciscus polylepis or the old name Telestes polylepis), which part of year, during dry periods, lives in sinkholes, just like the rare species Olm (Proteus anguinus) from the Dinara-karst. A few years ago, in the stomach of a big trout, which I had fished in an estavelle in the region of Jezerane, I found surprisingly this interesting, strange endemic small fish. The trout had eaten it. In the whole territory of the Velebit and Dinara-karst, as well as in the region of the Herzegowina rivers, there lives a special kind of endemic small fish from the minnow (Phoxinellus) and dace (Leuciscus) family. This species mostly lives together with trout.